A passive optical network (PON) is a point-to-multipoint network topology, and usually includes an optical line terminal (OLT) device located at a central office, a plurality of optical network unit (ONU) devices located at a user end, and an optical distribution network (ODN) located between the OLT device and the plurality of ONU devices.
In the PON system, due to the point-to-multipoint network topology, a newly-added ONU device can send upstream service data to the OLT device through an upstream channel only after completing registration and activation at the OLT device. For an Ethernet passive optical network (EPON) system, an OLT device receives, by opening a quiet window, a registration response packet sent by a newly-added ONU device through an upstream channel, to assign a logical link identifier (LLID) to the newly-added ONU device based on a media access control (MAC) address carried in the registration response packet, and complete ranging for the newly-added ONU device. For a gigabit-capable passive optical network (GPON) system, an OLT device receives, by opening a quiet window, a registration response packet sent by a newly-added ONU device, to assign an ONU ID based on a serial number (SN) carried in the registration response packet, and further complete ranging for the newly-added ONU device.
After completing registration, registered ONU devices send upstream service data to the OLT device through the upstream channel through time division multiple access (TDMA) in upstream sending timeslots assigned by the OLT device, to avoid a conflict, between upstream service data sent by the different ONU devices, on the upstream channel. In addition, to avoid a conflict between the registration response packet and the upstream service data on the upstream channel, during registration of the newly-added ONU device, the OLT stops granting bandwidth to the registered ONU device. In particular, the registered ONU stops sending upstream service data.
In the PON system, the registered ONU device can send the upstream service data only after the quiet window ends. Consequently, a relatively large delay exists during sending of the upstream service data, and a system delay requirement of a low delay service cannot be met. Therefore, an effective solution urgently needs to be provided to eliminate a delay caused by windowing activation for the ONU.